Hybrid electric vehicle axle with two motors

ABSTRACT

Provided herein is an electric axle assembly including a first motor-generator assembly, a second motor generator assembly, an axle housing, a first axle half shaft drivingly connected to the first motor-generator assembly and a second axle half shaft drivingly connected to the second motor-generator assembly. The first and second motor-generator assemblies each include a motor-generator and a housing and gear carrier portion. The axle housing includes a first axle tube portion, a second axle tube portion, a center portion, and an opening extending through the center portion of the axle housing, wherein the first axle tube portion and the second axle tube portion are disposed on axial opposite sides of the central portion. The first and second half shafts extended into the opening of the axle housing, and the first motor-generator assembly and the second motor-generator assembly are connected to the axle housing assembly.

RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/434,114 filed Dec. 14, 2016, which is incorporated herein byreference in its entirety.

BACKGROUND

There is an increasing interest in hybrid and pure electric vehicles dueto urban air pollution and greenhouse gas carbon emission regulations.One type of vehicle hybridization technology used is a parallel hybridsystem where one axle is combustion engine powered and another axle ispowered by one or more electric axle motors. Another type of system ispurely electric drive that does not utilize an internal combustionengine for powering the driveline.

Current technology electrified vehicle axles have offered a limitedability to incorporate dynamic torque vectoring, where an amount oftorque delivered to each wheel is varied. In electrified vehicle axleswithout a wheel differential, dynamic torque vectoring has beenperformed by using two motors, wherein motors and a multi-stage helicalgear or planetary drive are used for each wheel. Alternately, a singlemotor can be used with a dual friction clutch and helical gear orplanetary drives one for wheel. Optionally, the single motor system iscombined with mechanical propulsion from an internal combustion enginein a single rear drive unit and a shift system to incorporate a parttime torque vectoring capability. Such systems, however, are bulky, hardto package, costly and inefficient.

It would be advantageous to develop an electric axle which can operateefficiently in a small package and utilize currently tooled high volumecomponents.

SUMMARY

Provided herein is an electric axle assembly including a firstmotor-generator assembly, a second motor generator assembly, an axlehousing, a first axle half shaft drivingly connected to the firstmotor-generator assembly and a second axle half shaft drivinglyconnected to the second motor-generator assembly. The firstmotor-generator assembly includes a motor-generator and a housing andgear carrier portion. The second motor-generator assembly includes amotor-generator and a housing and gear carrier portion. The axle housingincludes a first axle tube portion, a second axle tube portion, a centerportion, and an opening extending through the center portion of the axlehousing, wherein the first axle tube portion and the second axle tubeportion are disposed on axial opposite sides of the central portion. Thefirst axle half shaft drivingly connected the first motor-generatorassembly at a first axial end thereof and drivingly connected to a firstwheel assembly at a second axial end thereof. The second axle haft shaftdrivingly connected to the second motor-generator assembly at a firstaxial end thereof and drivingly connected to a second wheel assembly atsecond axial end thereof. The second axial ends of the first and secondhalf shafts extended into the opening of the axle housing, and the firstmotor-generator assembly and the second motor-generator assembly areconnected to the axle housing assembly.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

Novel features, as well as other advantages of the present invention areset forth with particularity in the appended claims. A betterunderstanding of the features and advantages of the present inventionwill be obtained by reference to the following detailed description thatsets forth illustrative embodiments, in which the principles of theinvention are utilized, and the accompanying drawings of which:

FIG. 1 is a partially exploded, perspective view of one preferredembodiment of an electric axle;

FIG. 2 is a partial, top-plan view of the electric axle shown in FIG. 1;and

FIG. 3 is a partial, cross-sectional view of the electric axle shown inFIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts of the present invention. Hence, specific dimensions,directions, orientations or other physical characteristics relating tothe embodiments disclosed are not to be considered as limiting, unlessexpressly stated otherwise.

FIG. 1 depicts an electric axle assembly 100 for a motor vehicleaccording to one preferred embodiment. The electric axle assembly 100includes an axle housing 102, a first motor assembly 104, and a secondmotor assembly 106, but is understood that the axle assembly 100 mayinclude additional assemblies. In some embodiments, the first motorassembly 104 and the second motor assembly 106 are parallel to eachother.

The first motor assembly 104 is coupled to the axle housing 102 and isin driving engagement with a first axle half shaft 108. In someembodiments, the first axle half shaft 108 is at least partiallydisposed in the axle housing 102. The second motor assembly 106 iscoupled to the axle housing 102 and is in driving engagement with asecond axle half shaft 110. In some embodiments, the second axle haftshaft 110 is at least partially disposed in the axle housing 102.

In some embodiments, the first motor assembly 104 and the second motorassembly 106 are directly coupled to the axle housing 102, each assemblydriving the axle half shaft 108, 110 respectively. In some embodiments,the first motor assembly 104 and second motor assembly 106 are integralwith the axle housing 102.

In some embodiments, the axle housing 102 is a hollow elongate memberthat at least partially encloses elements of the axle including axlehalf shafts 108, 110 of the motor vehicle. In some embodiments, the axlehousing 102 is a high volume “banjo” type axle housing. The “banjo” typeaxle housing allows for installation of the axle assembly 100 in a motorvehicle chassis with the use of existing suspension or service brakecomponents, however, it is understood that other styles of axle housingsmay be used.

In some embodiments, the axle housing 102 is a “banjo” style housingincluding a beam 120 having a first axle tube portion 122 and a secondaxle tube portion 124 and a central portion 116. The axle housing 102can be formed by any conventional methods. In some embodiments, the axlehousing 102 is formed of a stamped metal material and the shape thereofis refined using secondary operations, such as machining or weldingattachments thereto. The axle tube portions 122, 124 are disposed onopposite lateral sides of the central portion 116.

As shown in FIG. 1, in some embodiments, the axle housing 102 includessuspension mounting members or brackets 112 and brake mounting membersor brackets 114. In some embodiments, the axle assembly 100 includes twosets of suspension mounting brackets 112 positioned on an outer surface122 a, 124 a of the axle tube portions 122, 124. In some embodiments,the brackets 112 include mounting apertyres 112 a that permit afastener, such as a U-bolt (not shown) to be positioned through thebracket 112 to facilitate the coupling of a spring or other suspensioncomponent to the bracket 112. The suspension mounting bracket 112 can befixedly coupled to the axle housing 102 by any appropriate means, suchas, welding.

In some embodiments, the brake mounting members 114 are mounted to theouter surface 122a, 124a of the axle tube portions 122, 124, axiallyaway from the center portion 116. The brake mounting members 114 can beconfigured a conventional manner to mount a brake system (not shown),such as a brake caliper (not shown) and can be fixedly coupled to theaxle housing 102 by any appropriate means, such as welding.

The center portion 116 of the axle housing 102 includes an opening 118extending through the axle housing 102. In some embodiments, the centerportion 116 is generally cylindrical in shape connecting the axle tubeportion 122, 124 and defines the opening 118. In some embodiments, thecenter portion 116 may include a plurality of apertures 116 a are formedin the outer surface of the center portion 116 adjacent to the opening118. The apertures 116 a allow for attaching the center portion 116 tothe first motor assembly 104 and the second motor assembly 106 to theaxle housing 102. Such an attachment is typically performed by threadedfasteners including, but not limited to, bolts.

The first axle half shaft 108 is rotatably disposed in the first axletube portion 122 of the axle housing 102. The first axle half shaft 108has a first axial end 108 a and a second axial end 108 b. At least aportion of the first axle half shaft 108 including the first axial end108 extends outside of the first axle tube portion 122 and is attachedto a wheel hub configured for mounting a wheel assembly (not shown)thereto. The wheel assembly includes a wheel powered by the axleassembly 100. In some embodiments, the first axle tube portion 122 isconfigured to contain bearings (not shown) on which the first axle halfshaft 108 rotates. In some embodiments, the second axial end 108b of thefirst axle half shaft 108 extends through the center portion 116. Thesecond axial end 108 b can be a splined end that extends out of thecenter portion 116 is positioned within the opening 118 of the axlehousing 102. The splined end 126 is drivingly engaged with a portion ofthe first motor assembly 104.

The second axle half shaft 110 is rotatably disposed in the second axletube portion 124 of the axle housing 102. The second axle half shaft 110has a first axial end 110 a and a second axial end 110 b. The firstaxial end 100 a of the second axle half shaft 110 extends outside of thesecond axle tube portion 124 and is attached to a wheel hub configuredfor mounting a wheel assembly (not shown) thereto. The wheel assemblyincludes a wheel powered by the axle assembly 100. In some embodiments,the second axle tube portion 124 is configured to hold bearings (notshown) on which the second axle half shaft 110 rotates. In someembodiments, the second axial end 110 b extends through the second axletube 122 and the center portion 116. The second axial end 110 b is asplined end and is positioned within the opening 118 of the axle housing102. The splined end 110 b is drivingly engaged with a portion of thesecond motor assembly 106.

In some embodiments, the first motor assembly 104 includes a firstmotor-generator 130, a housing and gear carrier portion 132, amotor-generator output gear 134, and a drive gear 136. In someembodiments, the housing and gear carrier portion 132 houses the outputgear 134 and the drive gear 136.

The first motor assembly 104 is coupled to the axle housing 102 suchthat the first motor assembly 104 in driving engagement with the firstaxle half shaft 108. In some embodiments, the first motor-generator 130is coupled to the housing and gear carrier portion 132 and is in drivingengagement with the motor-generator output gear 134. The motor-generatoroutput gear 134 is in driving engagement with a rotor (not shown) of thefirst motor-generator 130. In some embodiments, the rotor isperpendicular to the output gear 134. The first motor-generator 130 isin electrical communication with a controller (not shown) and a battery(not shown).

In some embodiments, the first motor-generator 130 is mounted to thehousing and gear carrier portion 132. In some embodiments, the firstmotor-generator 130 is positioned perpendicular to the first and secondaxle tube portions 122, 124. In some embodiments, the first-motorgenerator 130 is positioned within the housing and gear carrier portion132.

In some embodiments, the drive gear 136 is rotatably mounted directly,to the housing and gear carrier portion 132 through bearings (notshown). In some embodiments, the drive gear 136 and the output gear 134are positioned at least partially within the opening 118 of the axlehousing 102.

In some embodiments, the housing and gear carrier portion 132 isdirectly coupled to the axle housing 102. As depicted in FIG. 1, thehousing and gear carrier portion 132 may include a plurality ofapertures 132 a which align with the plurality of apertures 116 a in thecentral portion 116 to allow for direct connection of the housing andgear carrier portion 132 to the axle housing 102. This additional allowsfor quick and easy access to the motor-generators 130, 138 in the eventthat service is required to axle without having to disassembly the axleassembly 100. In some embodiments, a portion of the housing and gearcarrier portion 132 is formed from a stamped metal and is coupledthereto in any conventional manner, such as by welding or through theuse of fasteners.

As shown in FIGS. 2-3, the motor-generator output gear 134 engages thedrive gear 136 while also allowing engaging the splined end 108 b of thefirst axle half shaft 108. In some embodiments, the housing and gearcarrier portion 132 hold bearings (shown in FIG. 3) that facilitaterotation of the motor-generator output gear 134 and the drive gear 136.

In some embodiments, the motor-generator output gear 134 and the drivegear 136 are spiral bevel gears drivingly engaged with one another. Thegears 134, 136 transfer power to and from the first axle half shaft 108and the first motor-generator 130. In some embodiments, the gears 134,136 provide a reducing drive ratio therebetween. Specifically, in someembodiments, the gears 134, 136 are a high numerical reduction spiralbevel gear set of about 7.0:1 is used to improve efficiency and allowthe first motor-generator 130 to be down sized.

As shown in FIGS. 1-3, in some embodiments, the motor-generator outputgear 134 and the drive gear 136 are configured perpendicular to oneanother, however, it is understood that the motor-generator output gear134 and the drive gear 136 may be configured at other angles or be othertypes of gears. In further embodiments, the first motor assembly 104 caninclude additional reducing gear sets to achieve a desired gearreduction depending on the application the axle assembly 100 is used.

In some embodiments, the second motor assembly 106 is coupled to theaxle housing 102 and is in driving engagement with a second axle halfshaft 110. The second motor assembly 106 includes a secondmotor-generator 138, a housing and gear carrier portion 140, amotor-generator output gear 142, and a drive gear 144. In someembodiments, the housing and gear carrier portion 140 houses the outputgear 142 and the drive gear 144.

In some embodiments, the second motor-generator 138 is coupled to thehousing and gear carrier portion 140 and is in driving engagement withthe motor-generator output gear 142.

In some embodiments, the second motor-generator 138 is coupled to thehousing and gear carrier portion 140 and is in driving engagement withthe motor-generator output gear 142. The motor-generator output gear 142is in driving engagement with a rotor (not shown) of the secondmotor-generator 138. In some embodiments, the rotor is perpendicular tothe output gear 142.

In some embodiments, the second motor-generator 138 is mounted to thehousing and gear carrier portion 140. In some embodiments, the secondmotor-generator 138 is positioned perpendicular to the first and secondaxle tube portions 122, 124. In some embodiments, the secondmotor-generator 138 is positioned within the housing and gear carrierportion 140. In some embodiments, the drive gear 144 is rotatablymounted directly to the housing and gear carrier portion 140 throughbearings (not shown). In some embodiments, the drive gear 144 and theoutput gear 142 are positioned at least partially within the opening 118of the axle housing 102.

In some embodiments, the housing and gear carrier portion 140 isdirectly coupled to the axle housing 102. As depicted in FIG. 1, thehousing and gear carrier portion 140 may include a plurality ofapertures 140a which align with the plurality of apertures 116a in thecentral portion 116 to allow for direct connection of the housing andgear carrier portion 140 to the axle housing 102. In some embodiments, aportion of the housing and gear carrier portion 140 is formed from astamped metal and is coupled thereto in any conventional manner, such asby welding or through the use of fasteners.

As shown in FIGS. 1-3, the motor-generator output gear 142 engages thedrive gear 144 while also allowing engaging the splined end 110 b of thesecond axle half shaft 110. In some embodiments, the housing and gearcarrier portion 140 hold bearings (shown in FIG. 3) that facilitaterotation of the motor-generator output gear 142 and the drive gear 144.

In some embodiments, the motor-generator output gear 142 and the drivegear 144 are spiral bevel gears drivingly engaged with one another. Thegears 142, 144 transfer power to and from the second axle half shaft 110and the second motor-generator 138. In some embodiments, the gears 142,144 provide a reducing drive ratio therebetween. Specifically, in someembodiments, the gears 142, 144 are a high numerical reduction spiralbevel gear set of about 7.0:1 to improve efficiency and allow the secondmotor-generator 138 to be down sized. In further embodiments, the secondmotor assembly 106 can include additional reducing gear sets to achievea desired gear reduction depending on the application the axle assembly100 is used.

As shown in FIGS. 1-3, in some embodiments, the motor-generator outputgear 142 and the drive gear 144 are configured perpendicular to oneanother, however, it is understood that the motor-generator output gear142 and the drive gear 144 may be configured at other angles or be othertypes of gears. In further embodiments, the second motor assembly 106can include additional reducing gear sets to achieve a desired gearreduction depending on the application the axle assembly 100 is used.

The housing and gear carrier portion 140 facilitates a mounting of thesecond motor-generator 138 and the drive gear 144 while also providingmounting points for the second motor assembly 106 to be coupled to theaxle housing 102. This additional allows for quick and easy access tothe motor-generator 138 in the event that service is required to axlewithout having to disassembly the axle assembly 100. In someembodiments, a portion of the housing and gear carrier portion 140 maybe formed from a stamped metal and carriers for the motor-generatoroutput gear 142 and the drive gear 144 may be coupled thereto in anyconventional manner, such as by welding or through the use of fasteners.

The motor-generators 130,138 are in electrical communication with acontroller (not shown) and an energy storage device (not shown). In someembodiments, the energy storage device can be a battery. It is to beunderstood that the battery can be replaced with a fuel cell for a fuelcell electric vehicle drivetrain (FCEV). Depending on the electricalcontrol of the motor-generator 130, 138 using the controller, themotor-generator 130, 138 may apply force to or retard a portion of theaxle half shaft 108, 110 it is drivingly engaged with.

In some embodiments, the controller is configured to receive signalsfrom a plurality of sensors (not shown) positioned on or off the axleassembly 100. The sensors provide signals indicative of variousparameters of the axle assembly 100 including, but not limited to,steering wheel angle, angular acceleration, vehicle lateralacceleration, wheel speed, vehicle speed, throttle position sensorvalues, gear selector position, user selectable mode configurations, andthe like, or some combination thereof. The electronic controller alsoreceives one or more control inputs. The electronic controller bysending and receiving signals to motor-generators 130, 138 provides theability to incorporate torque vectoring and a limited slip tractionusing the appropriate electronic algorithm. In some embodiments, thecontroller can send signals to control the torque and speeds of eachmotor-generator to apply a vehicle yaw moment to aid in the vehicle turnin or cornering. Alternately, controller can monitor the left and rightwheel speeds and torques to determine if a low friction or splittraction event requires left to right wheel torque or speed control andthen send the required signals to the motor-generators 130, 138. In someembodiments, the controller provides the electric axle assembly 100 afail safe operation in the event that a either the first motor-generator130 or the second motor-generator 138 becomes inoperable.

In some embodiments, the motor-generators 130, 138 additionally provideelectrical energy during regenerative braking. When the motor-generator130, 138 retards portions of the electric axle 102, electric energy isgenerated within the motor-generator 130, 138. The electrical energyprovided during regenerative braking can be utilized to charge a battery(not shown) connected to the motor-generator 130, 138 through acontroller (not shown).

The electric axle assembly 100 as depicted eliminates the need for adifferential, thus saving weight, however, it is within the scope of theinvention for the electric axle assembly 100 to be adapted for use witha differential, thus allowing the blending of torque from two motors.

The electric axle assembly 100 can be used in front wheel drive and rearwheel drive vehicles. While not shown, it is understood that theelectric axle assembly 100 may be operated with an unpowered tag orpusher axle to form a multi-axle driveline.

The electric axle assembly 100 disclosed herein are applicable to HEV,EV and Fuel Cell Hybrid systems. It should be understood that electricor hybrid electric vehicles incorporating embodiments of the electricaxle assembly 100 disclosed herein are capable of including a number ofother powertrain components, such as, but not limited to, high-voltagebattery pack with a battery management system or ultracapacitor,on-board charger, DC-DC converters, a variety of sensors, actuators, andcontrollers, among others.

Those of skill will recognize that the various illustrative logicalblocks, modules, circuits, and algorithm steps described in connectionwith the embodiments disclosed herein, including with reference to thecontroller or control system described herein, for example, may beimplemented as electronic hardware, software stored on a computerreadable medium and executable by a processor, or combinations of both.To clearly illustrate this interchangeability of hardware and software,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled artisans may implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the preferred embodiments.

For example, various illustrative logical blocks, modules, and circuitsdescribed in connection with the embodiments disclosed herein may beimplemented or performed with a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. Software associated with such modules may reside in RAMmemory, flash memory, ROM memory, EPROM memory, EEPROM memory,registers, a hard disk, a removable disk, a CD-ROM, or any othersuitable form of storage medium known in the art. An exemplary storagemedium is coupled to the processor such that the processor readsinformation from, and write information to, the storage medium. In thealternative, the storage medium may be integral to the processor. Theprocessor and the storage medium may reside in an ASIC. For example, inone embodiment, a controller for use of control of the axle includes aprocessor (not shown).

In accordance with the provisions of the patent statutes, the presentinvention has been described in what is considered to represent itspreferred embodiments, however, it should be noted that the inventioncan be practiced otherwise than as specifically illustrated anddescribed without departing from its scope or spirit. It should be notedthat the description above has provided dimensions for certaincomponents or subassemblies. The mentioned dimensions, or ranges ofdimensions, are provided in order to comply as best as possible withcertain legal requirements, such as best mode. However, the scope of theinventions described herein are to be determined solely by the languageof the claims, and consequently, none of the mentioned dimensions is tobe considered limiting on the inventive embodiments, except in so far asany one claim makes a specified dimension, or range of thereof, afeature of the claim.

While preferred embodiments have been shown and described herein, itwill be obvious to those skilled in the art that such embodiments areprovided by way of example only. Numerous variations, changes, andsubstitutions will now occur to those skilled in the art withoutdeparting from the invention. It should be understood that variousalternatives to the embodiments described herein may be employed inpracticing the invention. It is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

What is claimed:
 1. An electric axle assembly comprising: a firstmotor-generator assembly including a motor-generator and a housing andgear carrier portion; a second motor-generator assembly including amotor-generator and a housing and gear carrier portion; an axle housingincluding a first axle tube portion, a second axle tube portion, acenter portion, and an opening extending through the center portion ofthe axle housing, wherein the first axle tube portion and the secondaxle tube portion are disposed on axial opposite sides of the centralportion; a first axle half shaft drivingly connected the firstmotor-generator assembly at a first axial end thereof and drivinglyconnected to a first wheel assembly at a second axial end thereof; and asecond axle haft shaft drivingly connected to the second motor-generatorassembly at a first axial end thereof and drivingly connected to asecond wheel assembly at second axial end thereof, wherein the secondaxial ends of the first and second half shafts extended into the openingof the axle housing, and wherein the first motor-generator assembly andthe second motor-generator assembly are connected to the axle housingassembly.
 2. The electric axle assembly of claim 1, wherein the firstmotor-generator assembly further comprises a motor-generator output gearand a drive gear, and wherein the second motor-generator assemblyfurther comprises a motor-generator output gear and a drive gear.
 3. Theelectric axle assembly of claim 1, wherein the housing and gear carrierportions house the motor-generator output gears and the drive gears. 4.The electric axle assembly of claim 1, wherein the motor-generatorassemblies are positioned perpendicular to the tube axle portions. 5.The electric axle assembly of claim 1, wherein the motor-generatoroutput gears and the drive gears are bevel gears.
 6. The electric axleassembly of claim 5, wherein the motor-generator output gears and thedrive gears have a reducing gear ratio.
 7. The electric axle assembly ofclaim 1, wherein the first motor generator is directly connected to thefirst housing and carrier gear portion and the second motor generator isdirectly connected to the second housing and carrier gear portion. 8.The electric axle assembly of claim 1 further comprising a firstsuspension mounting member coupled to the first axle tube portion and asecond suspension mounting member coupled to the second axle tubeportion.
 9. The electric axle assembly of claim 1, wherein themotor-generators are integral with the housing and gear carrier portion.10. The electric axle assembly of claim 2, wherein the motor-generatoroutput gears are perpendicular to the drive gears.
 11. The electric axleassembly of claim 1, wherein the first motor assembly and the secondmotor assembly are parallel to each other.
 12. The electric axleassembly of claim 1, wherein the axle housing is a banjo-type housing.